Magnetic tunnel junction device with spin-filter structure

ABSTRACT

A magnetic device includes: a conductive layer into which current is injected in a first direction, the conductive layer causing spin Hall effect or Rashba effect; a ferromagnetic layer disposed in contact with the conductive layer such that the ferromagnetic layer and the conductive layer are stacked on each other, a magnetization direction of the ferromagnetic layer being switched; and a spin filter structure having a fixed magnetization direction, the spin filter structure being disposed on at least one of the opposite side surfaces of the first direction of the conductive layer to inject spin-polarized current into the conductive layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional application is a continuation of U.S. patentapplication Ser. No. 15/639,662 filed Jun. 30, 2017, which claimspriority under 35 U.S.C. § 119 to Korea Patent Application No.10-2017-0000532 filed on Jan. 3, 2017, the entireties of which arehereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to magnetic tunnel junction devices and,more particularly, to a magnetic tunnel junction device which generatesa spin orbit torque.

BACKGROUND

A ferromagnetic body means a material that is spontaneously magnetizedeven though a strong magnetic field is not applied thereto from theoutside. In a magnetic tunnel junction structure (first magneticbody/insulator/second magnetic body) in which an insulator is interposedbetween two ferromagnetic bodies, an electric resistance variesdepending on relative magnetization directions of two magnetic layers,i.e., a tunnel magnetoresistance (TMR) effect occurs. The TMR effectoccurs because up-spin and down-spin electrons flow at different degreesat the magnetic tunnel junction structure while tunneling an insulator.

According to the law of action and reaction that is Newton's third lawof motion, if the magnetization direction may control a flow of current,it is also possible to control a magnetization direction of the magneticlayer by applying current due to the reaction. If current is applied tothe magnetic tunnel junction structure in a direction perpendicular to afilm surface, the current spin-polarized by a first magnetic body(magnetization pinned magnetic layer, hereinafter referred to as “pinnedmagnetic layer”) transfers its spinning angular momentum while passingthrough a second magnetic body (magnetization free magnetic layer,hereinafter referred to as “free magnetic layer”). A torque felt bymagnetization due to the transfer of spinning angular momentum is calleda spin-transfer torque (STT). Use of the spin-transfer torque make itpossible to fabricate a device for reversing the free magnetic layer orcontinuously rotating the free magnetic layer or a device for moving amagnetic domain wall of the free magnetic layer.

Moreover, the magnetic tunnel junction may lead to magnetizationreversion of a free magnetic layer or movement of a magnetic domainstructure by using a spin-orbit torque (SOT) generated by spin Halleffect or Rashba effect when in-plane current flows in a conducting wireadjacent to the free magnetic layer.

A magnetization reversing device using a spin-orbit torque is disclosedin U.S. Pat. No. 8,416,618 B2.

As utilization of mobile devices and Internet of things (IoT) electronicdevices continues to increase, low-power, small-area, ultrahigh-speed,and non-volatile memories have come into spotlight.

SUMMARY

A feature of the present invention is to provide a magnetic device inwhich spin-polarized current is provided to a conductive layer, which isin contact with a free magnetic layer to provide in-plane current,through a spin filter to additionally provide spin accumulation to aninterface between the conductive layer and the free magnetic layer andfield-free switching is possible where an external magnetic field doesnot need to be applied when a magnetization direction of a spin filterstructure is set to a plane perpendicular direction.

Another feature of the present disclosure is to provide a magneticdevice in which spin-polarized current is provided to a conductivelayer, which is in contact with a free magnetic layer to providein-plane current, through a spin filter structure to increase spinaccumulation caused by spin Hall effect at the interface between theconductive layer and the free magnetic layer to easily switch the freemagnetic layer.

Another feature of the present application is to provide a magneticdevice in which spin-polarized current is provided to a conductivelayer, which is in contact with a free magnetic layer to providein-plane current, through a spin filter structure to provide spinaccumulation caused by spin Hall effect and spin accumulation having anin-plane direction to the interface between the conductive layer and thefree magnetic layer.

Another feature of the present application is to provide a magneticdevice in which spin-polarized current is provided to a conductivelayer, which is in contact with a free magnetic layer to providein-plane current, to provide spin accumulation to the interface betweenthe conductive layer and the free magnetic layer.

Another feature of the present invention is to provide a devicestructure which enhances spin splitting efficiency to increase theeffect of spin-orbit torque (SOT).

Another feature of the present application is to improve a structure ofa magnetic memory.

The features of the present disclosure are not limited to the foregoing,but other features not described herein will be clearly understood bythose skilled in the art from the following descriptions.

A magnetic device according to an example embodiment of the presentdisclosure includes: a conductive layer into which current is injectedin a first direction, the conductive layer causing spin Hall effect orRashba effect; a ferromagnetic layer disposed in contact with theconductive layer such that the ferromagnetic layer and the conductivelayer are stacked on each other, a magnetization direction of theferromagnetic layer being switched; and a spin filter structure having afixed magnetization direction, the spin filter structure being disposedon at least one of the opposite side surfaces of the first direction ofthe conductive layer to inject spin-polarized current into theconductive layer.

In an example embodiment, spin polarization of the spin filter structuremay be greater than 0 and equal to or smaller than 1.

In an example embodiment, the spin filter structure may be ahalf-metallic ferromagnet.

In an example embodiment, the half-metallic ferromagnet may include atleast one of a Heusler alloy, magnetite (Fe₃O₄), and lanthanum strontiummanganite (LSMO).

In an example embodiment, the spin filter structure may include aferromagnet. A magnetization direction of the spin filter structure maybe parallel or antiparallel to a magnetization direction of theferromagnetic layer.

In an example embodiment, a magnetization direction of the spin filterstructure may be antiparallel at opposite sides of the conductive layerwhen the spin filter structure is disposed on opposite side surfaces ofthe conductive layer.

In an example embodiment, the conductive layer and the ferromagneticlayer may be aligned with each other.

In an example embodiment, the free magnetic layer may have perpendicularmagnetic anisotropy (PMA).

In an example embodiment, a spin-flip diffusion length of the conductivelayer may be between 3 and 4 nanometers.

A magnetic tunnel junction device according to an example embodiment ofthe present disclosure includes: a magnetic tunnel junction including apinned magnetic layer, a free magnetic layer, and a tunnel barrier layerinterposed between the pinned magnetic layer and the free magneticlayer; a conductive pattern to which in-plane current flows, theconductive pattern being disposed adjacent to the free magnetic layer ofthe magnetic tunnel junction to cause spin Hall effect or Rashba effectto apply a spin torque to the free magnetic layer of the magnetic tunneljunction; and a spin filter structure disposed on at least one of theopposite side surfaces of the conductive pattern in a direction in whichin-plane current is applied. The spin filter structure may filterinjected current to control the amount and direction of a spin and tosupply the filtered current to the conductive pattern.

In an example embodiment, the pinned magnetic layer may have a syntheticantiferromagnetic structure including a first pinned magnetic layer, anon-magnetic layer for a pinned magnetic layer, and a second pinnedmagnetic layer which are sequentially stacked. Each of the first pinnedmagnetic layer and the second pinned magnetic layer may independentlyinclude at least one of Fe, Co, Ni, Gd, B, Si, Zr, and a combinationthereof. The non-magnetic layer for a pinned magnetic layer may includeat least one of Ru, Ta, Cu, Pt, Pd, W, Cr, and a combination thereof.

In an example embodiment, the pinned magnetic layer may have anexchange-biased antiferromagnetic structure including anantiferromagnetic layer, a first pinned magnetic layer, a non-magneticlayer for a pinned magnetic layer, and a second pinned magnetic layerwhich are sequentially stacked. The antiferromagnetic layer may beformed of one selected from the group consisting of Pt, Ir, Fe, Mn, anda combination thereof. Each of the first pinned magnetic layer and thesecond pinned magnetic layer may independently include at least one ofFe, Co, Ni, Gd, B, Si, Zr, and a combination thereof. The non-magneticlayer for a pinned magnetic layer may include at least one of Ru, Ta,Cu, Pt, Pd, W, Cr, and a combination thereof.

In an example embodiment, the tunnel barrier layer may include at leastone of AlO_(x), MgO, TaO_(x), ZrO_(x), and a combination thereof.

In an example embodiment, the conductive pattern may provide aspin-orbit torque (SOT) resulting from a spin-orbit coupling forcebetween the free magnetic layer and the conductive pattern. Theconductive pattern may be formed of one selected from the groupconsisting of Cu, Ta, Pt, W, Bi, Ir, Mn, Ti, Cr, Pd, Re, Os, Hf, Mo, Ru,and a combination thereof.

In an example embodiment, the free magnetic layer may include at leastone magnetic domain structure.

In an example embodiment, the conductive pattern applying the in-planecurrent may include an antiferromagnetic layer and a ferromagnetic layerwhich are sequentially stacked, the antiferromagnetic layer may bedisposed adjacent to the free magnetic layer, the ferromagnetic layermay have an in-plane magnetization direction, the conductive pattern mayprovide an in-plane exchange bias magnetic field to the free magneticlayer, and the free magnetic layer may be switched without an externalmagnetic field.

In an example embodiment, the magnetic tunnel junction device mayfurther include a dipole field non-magnetic layer and a dipole fieldmagnetic layer having an in-plane magnetization direction which aresequentially stacked adjacent to the pinned magnetic layer. The dipolefield non-magnetic layer may be disposed adjacent to the pinned magneticlayer. The free magnetic layer may be switched without an externalmagnetic field.

In an example embodiment, the magnetic tunnel junction device mayfurther include an auxiliary insulating layer disposed between theconductive pattern and the free magnetic layer.

In an example embodiment, the conductive patterns may include aconducting wire non-magnetic layer and a conducting wire ferromagneticlayer which are sequentially stacked. The conducting wire ferromagneticlayer may include an in-plane magnetization direction component.

In an example embodiment, the conductive pattern may include aconducting wire ferromagnetic layer and a conducting wire non-magneticlayer which are sequentially stacked. A non-magnetic layer may beprovided between the conducting wire ferromagnetic layer and the freemagnetic layer.

A magnetic memory device according to an example embodiment of thepresent disclosure includes: a plurality of magnetic tunnel junctionsarranged in a matrix form; a first conductive pattern disposed adjacentto a free magnetic layer of the magnetic tunnel junction; and a spinfilter structure disposed on at least one of the opposite side surfacesof the first conductive pattern. The conductive pattern may provide aspin-orbit torque resulting from a spin-orbit coupling force between thefree magnetic layer and the conductive pattern. The spin filterstructure may supply spin-polarized current to the conductive pattern.

In an example embodiment, the first conductive pattern may be formed ofone selected from the group consisting of Cu, Ta, Pt, W, Bi, Ir, Mn, Ti,Cr, Pd, Re, Os, Hf, Mo, Ru, and a combination thereof.

In an example embodiment, the first conductive pattern may applyin-plane current and may include an antiferromagnetic layer. The firstconductive pattern may provide an in-plane exchange bias magnetic fieldto the free magnetic layer.

In an example embodiment, the free magnetic layer may include at leastone magnetic domain structure.

In an example embodiment, the first conductive pattern may applyin-plane current and includes an antiferromagnetic layer and aferromagnetic layer which are sequentially stacked, theantiferromagnetic layer may be disposed adjacent to the free magneticlayer, the antiferromagnetic layer may have an in-plane magnetizationdirection, the first conductive pattern may provide an in-plane exchangebias magnetic field to the free magnetic layer, and the free magneticlayer may be switched without an external magnetic field.

In an example embodiment, the magnetic memory device may further includea dipole field non-magnetic layer and a dipole field magnetic layerhaving an in-plane magnetization direction which are sequentiallystacked adjacent to the pinned magnetic layer. The dipole fieldnon-magnetic layer may be disposed adjacent to the pinned magneticlayer.

In an example embodiment, the magnetic memory device may further includean auxiliary insulating layer disposed between the first conductivepattern and the free magnetic layer.

In an example embodiment, the first conductive pattern may include afirst conductive pattern non-magnetic layer and a first conductivepattern magnetic layer which are sequentially stacked. The firstconductive pattern magnetic layer may include an in-plane magnetizationdirection component.

In an example embodiment, the first conductive pattern may include afirst conductive pattern magnetic layer and a first conductive patternnon-magnetic layer which are sequentially stacked. A non-magnetic layermay be provided between the first conductive pattern magnetic layer andthe free magnetic layer.

In an example embodiment, the first conductive patterns may extendparallel to each other on a substrate plane in a first direction. A freemagnetic layer of each of the magnetic tunnel junctions arranged in thefirst direction may be periodically disposed adjacent to the firstconductive pattern. The magnetic memory device may further include asecond conductive pattern which is electrically connected to a pinnedmagnetic layer 140 of each of the magnetic tunnel junctions 101 arrangedin a second direction perpendicular to the first direction and extendson the substrate plane in the second direction.

In an example embodiment, the first conductive patterns may beperiodically disposed on a substrate plane in a first direction. A freemagnetic layer of each of the magnetic tunnel junctions arranged in thefirst direction may be periodically disposed adjacent to the firstconductive pattern. The magnetic memory device may further include: asecond conductive pattern which is electrically connected to a pinnedmagnetic layer of each of the magnetic tunnel junctions arranged in thefirst direction and extends on the substrate plane in the firstdirection; a third conductive pattern which is connected to one end ofeach of the first conductive patterns arranged in the first directionand extends in the first direction; and a fourth conductive patternwhich is connected to the other end of each of the first conductivepatterns arranged in the second direction and extends in the seconddirection.

In an example embodiment, the first conductive pattern may extend on asubstrate plane in a first direction. A free magnetic layer of each ofthe magnetic tunnel junctions arranged in the first direction may beperiodically disposed adjacent to the first conductive pattern. Themagnetic memory device may further include: selection transistors whichare electrically connected to pinned magnetic layers of the magnetictunnel junctions, respectively; a second conductive pattern which iselectrically connected to source/drain of each of the selectiontransistors arranged in the first direction and extends on the substrateplane in the first direction; and a third conductive pattern which isconnected to a gate of each of the selection transistors arranged in asecond direction perpendicular to the first direction.

In an example embodiment, the first conductive pattern may extend on asubstrate plane in a first direction. A free magnetic layer of each ofthe magnetic tunnel junctions arranged in the first direction may beperiodically disposed adjacent to the first conductive pattern. Themagnetic memory device may further include: selection transistors whichare electrically connected to pinned magnetic layers of the magnetictunnel junctions, respectively; a second conductive pattern which iselectrically connected to source/drain of each of the selectiontransistors arranged in a second direction perpendicular to the firstdirection and extends on the substrate plane in the second direction;and a third conductive pattern which is connected to a gate of each ofthe selection transistors arranged in the first direction.

In an example embodiment, the first conductive pattern may extend on asubstrate plane in a first direction. A free magnetic layer of each ofthe magnetic tunnel junctions arranged in the first direction may beperiodically disposed adjacent to the first conductive pattern. Themagnetic memory device may further include: a second conductive patternwhich is electrically connected to each of the pinned magnetic layers ofthe magnetic tunnel junctions arranged in the first direction; a thirdconductive pattern which is connected to one end of each of the firstconductive patterns arranged in the first direction and extends in thefirst direction; selection transistors which are connected to the otherend of each of the first conductive patterns; a fourth conductivepattern which are connected to source/drain of each of the selectiontransistors arranged in the first direction and extends in the firstdirection; and a fifth conductive pattern which is connected to a gateof each of the selection transistors arranged in a second directionperpendicular to the first direction and extends in the seconddirection.

In an example embodiment, the first conductive pattern may extend on asubstrate plane in a first direction. A free magnetic layer of each ofthe magnetic tunnel junctions arranged in the first direction may beperiodically disposed adjacent to the first conductive pattern. Themagnetic memory device may further include: selection transistors whichare connected to pinned magnetic layers of the magnetic tunneljunctions, respectively; a second conductive pattern which is connectedto source/drain of each of the selection transistors arranged in thefirst direction; a third conductive pattern which is connected to a gateof each of the selection transistors arranged in a second directionperpendicular to the first direction and extends in the seconddirection; a fourth conductive pattern which is connected to one end ofeach of the first conductive patterns arranged in the first directionand extends in the first direction; and a fifth conductive pattern whichis connected to the other end of each of the first conductive patternsarranged in the first direction and extends in the first direction.

In an example embodiment, the first conductive pattern may extend on asubstrate plane in a first direction. A free magnetic layer of each ofthe magnetic tunnel junctions arranged in the first direction may beperiodically disposed adjacent to the first conductive pattern. Themagnetic memory device may further include: a second conductive patternwhich is electrically connected to each of the pinned magnetic layers ofthe magnetic tunnel junctions arranged in the first direction and extendin a second direction perpendicular to the first direction; a firstselection transistor which is connected to one end of each of the firstconductive patterns; a second selection transistors which is connectedto the other end of each of the first conductive patterns; a thirdconductive pattern which is connected to source/drain of the firstselection transistor disposed in the first direction and extends in thefirst direction; a fourth conductive pattern which is connected tosource/drain of the second selection transistor disposed in the firstdirection and extends in the first direction; and a fifth conductivepattern which connects a gate of the first selection transistor arrangedin a second direction perpendicular to the first direction and a gate ofthe second selection transistor to each other to extend in the seconddirection.

In an example embodiment, the first conductive pattern may extend on asubstrate plane in a first direction. A free magnetic layer of each ofthe magnetic tunnel junctions arranged in the first direction may beperiodically disposed adjacent to the first conductive pattern. Themagnetic memory device may further include: a first selection transistorwhich is connected to each of the pinned magnetic layers of the magnetictunnel junctions; a second transistor which is connected to one end ofeach of the first conductive patterns; a second conductive pattern whichis connected to source/drain of the first selection transistor disposedin the first direction; a third conductive pattern which connects theother ends of the first conductive patterns arranged in the firstdirection to each other and extends in the first direction; a fourthconductive pattern which connects sources/drains of the second selectiontransistors arranged in the first direction to each other and extends inthe first direction; a fifth conductive pattern which connects gates ofthe first selection transistors arranged in a second directionperpendicular to the first direction to each other and extends in thesecond direction; and a sixth conductive pattern which connect gates ofthe second selection transistors arranged in the second direction toeach other and extends in the second direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more apparent in view of the attacheddrawings and accompanying detailed description. The embodiments depictedtherein are provided by way of example, not by way of limitation,wherein like reference numerals refer to the same or similar elements.The drawings are not necessarily to scale, emphasis instead being placedupon illustrating aspects of the present disclosure.

FIG. 1 is a perspective view of a conventional magnetic device using aspin-orbit torque.

FIG. 2 is a conceptual diagram of a magnetic device including a spinfilter structure according to an example embodiment of the presentdisclosure.

FIG. 3 illustrates position-dependent spin accumulation at the magneticdevice in FIG. 2.

FIG. 4 illustrates dependencies of a damping-like spin torque T_(D) onfour parameters θ_(SH), t_(N), l_(sf) ^(N), and w.

FIG. 5 illustrates dependencies of a field-like spin torque T_(F) onfour parameters θ_(SN) t_(N), l_(sf) ^(N), and w.

FIG. 6 is a conceptual diagram of a magnetic device including a spinfilter structure according to another example embodiment of the presentdisclosure.

FIGS. 7 to 9 illustrate magnetic devices according to other exampleembodiments of the present disclosure, respectively.

FIG. 10 illustrates spin accumulation depending on magnetizationdirections of a spin filter structure and a ferromagnet according toanother example embodiment of the present disclosure.

FIG. 11 illustrates magnetic tunnel devices according to another exampleembodiment of the present disclosure.

FIG. 12 illustrates magnetic tunnel devices according to another exampleembodiment of the present disclosure.

FIGS. 13 to 20 are conceptual diagrams of magnetic tunnel junctiondevices according to other example embodiments of the presentdisclosure, respectively.

FIGS. 21 to 28 illustrate magnetic memory devices according to otherexample embodiments of the present disclosure, respectively.

DETAILED DESCRIPTION

In recent years, there are becoming attractive material and devicetechnologies which may significantly improve write performance of amemory by easily reversing (switching) a magnetization direction of aferromagnet (FM) with low energy, from a spin-orbit torque (SOT)generated by spin Hall effect caused by strong spin-orbit coupling (SOC)of the non-magnet or Rashba effect of a ferromagnet/double layerinterface in a double-layer structure including the ferromagnet (FM) anda non-magnet (NM).

FIG. 1 is a perspective view of a conventional magnetic device using aspin-orbit torque.

Referring to FIG. 1, when in-plane current is j_(x) injected into anon-magnetic layer 10 in an x axis direction, spin current is generatedsuch that a spin polarized in a y axis direction is transported in a zaxis direction by spin Hall effect occurring in the non-magnetic layer10. Thus, spin accumulation may be provided to an interface of thenon-magnetic layer 10/a free magnetic layer 20. A polarization directionof a spin accumulated on a top surface of the non-magnetic layer 10 is+y direction, and a polarization direction of a spin accumulated on abottom surface of the non-magnetic layer 10 is −y direction. If Rashbaeffect exists at the interface of the non-magnetic layer 10/the freemagnetic layer 20, spin accumulation polarized in the +y direction (or−y direction) may be provided on a top surface of the non-magnetic layer10 when in-plane current j_(x) is injected into the non-magnetic layer10 in the x axis direction.

The in-plane current flowing to the non-magnetic layer 10 generates spinaccumulation caused by spin Hall effect in the non-magnetic layer 10 orRashba effect at a ferromagnetic/non-magnetic interface, and theaccumulated spin provides a spin torque to a ferromagnet. Since both thespin Hall effect and the Rashba effect arises from strong spin-orbitcoupling, a spin torque generated therefrom is called a spin-orbittorque (SOT). Thus, out-of-plane magnetization of a ferromagnetic layermay be switched from a spin-orbit torque generated when in-plane currentis applied in a ferromagnetic/non-magnetic double structure. An SOTswitching mechanism provides fast switching and device stability.However, the SOT switching mechanism has several disadvantages. It isreported that switching current required for the SOT switching isgreater than conventional current for a spin-transfer torque.

In the case that in-plane is injected, spin-orbit coupling effectgenerates spin accumulation at a ferromagnetic/non-magnetic interfaceand the spin accumulation causes a spin-orbit torque at theferromagnetic layer. Thus, a method for providing a device structuresuitable to reduce switching current is to increase spin accumulation ata ferromagnetic/non-magnetic interface. To this end, we propose astructure where a ferromagnetic spin filter structure is abutted on aside surface of a non-magnetic layer. Apart from spin Hall effect,current supplied through the spin filter structure generates spinaccumulation corresponding to a magnetization direction of the spinfilter structure at a ferromagnetic/non-magnetic interface. That is,when in-plane current is applied to a conducting wire, the spin filterstructure itself may cause a spin transfer torque corresponding to themagnetization of the spin filter structure at the ferromagnetic layer.Accordingly, a spin torque emerging when in-plane current is applied ina non-magnetic/ferromagnetic double structure on which the spin filterstructure is added is approximately given by a vector sum of aspin-orbit torque caused by spin-orbit coupling and a spin-transfertorque generated from spin filter effect. The spin filter structure mayadditionally provide spin accumulation to apply the spin-orbit torque orthe spin-transfer torque. Thus, critical current may be reduced toreduce power consumption.

By suitably adjusting the magnetization direction of the spin filterstructure, spin accumulation occurring from the spin filter structuremay be additively coupled with the spin accumulation caused by spin Halleffect. For example, in the case that a spin direction by the spin Halleffect is y axis direction, spin accumulation may be summed in the yaxis direction if the magnetization direction of the spin filterstructure is aligned in the y axis direction. Thus, additive spinaccumulation from the spin filter structure may increase a spin torqueacting on the ferromagnetic layer.

When the magnetization direction of the spin filter structure is z axisdirection, spin-polarized current may provide spin accumulation of the zaxis direction and spin accumulation caused by the spin Hall effect mayprovide spin accumulation in the y axis direction. The vector sum mayincrease a size of the total spin torque and may cause magnetizationreversion of the free magnetic layer (the ferromagnetic layer) withoutan external magnetic field.

When in-plane current is injected into a non-magnet (NM) in a non-magnet(NM)-ferromagnet (FM) junction structure, a spin-orbit torque may becaused by strong spin-orbit coupling (SOC) between the non-magnet (NM)and the ferromagnet (FM) to easily switch a magnetization direction ofthe ferromagnet (FM).

In the case of a conventional method, spin splitting occurs due tospin-orbit coupling (SOC) effect when in-plane current is injected intothe non-magnet (NM). Among all spins, half the spins migrate to aferromagnetic layer joined to a non-magnetic layer and the other spinsmigrate in an opposite direction. The spins migrating to theferromagnetic layer causes a spin-orbit torque (SOT) to change amagnetization (M) direction of the ferromagnetic layer. However, sincecurrent is injected into a non-magnetic layer in a conventionalstructure, spin splitting efficiency does not exceed 50 percent.

A magnetic device according to an example embodiment of the presentdisclosure has a stacked structure in which a ferromagnetic layer and anon-magnetic layer are stacked. A spin filter (SF) structure is abuttedon at least one side of a direction in which in-plane current flows fromthe non-magnetic layer. The spin filter structure may convert currentinjected into the spin filter structure into spin current spin-polarizedin one direction. The direction of the spin polarization may depend on amagnetization of the spin filter structure. Thus, the spin filterstructure allows the non-magnetic layer to receive spin current which ismore polarized in a specific direction. The spin current may be spincurrent polarized in the magnetization direction of the ferromagneticlayer. That is, the spin filter structure may control the amount anddirection of the spin filter structure to enhance efficiency of aspin-orbit torque between the ferromagnetic layer and the non-magneticlayer. The spin-polarized current generates an additional spin chemicalpotential difference at a ferromagnetic/non-magnetic interface from thespin filter structure and may cause a spin transfer torque (STT) in theferromagnetic layer.

A suitable magnetization direction of the spin filter structure mayremove an external magnetic field required for magnetization switching.

Example embodiments will now be described more fully with reference tothe accompanying drawings, in which some example embodiments are shown.Example embodiments may, however, be embodied in many different formsand should not be construed as being limited to the embodiments setforth herein; rather, these example embodiments are provided so thatthis disclosure will be thorough and complete, and will fully convey thescope of example embodiments of the present disclosure to those ofordinary skill in the art. In the drawings, the thicknesses of layersand regions are exaggerated for clarity. Like reference charactersand/or numerals in the drawings denote like elements, and thus theirdescription may be omitted.

In the present disclosure, we have theoretically analyzed the effect ofa spin filter structure with respect to a non-magnetic/ferromagneticdouble structure. Hereinafter, the operation principle of the presentdisclosure will now be described.

FIG. 2 is a conceptual diagram of a magnetic device including a spinfilter structure according to an example embodiment of the presentdisclosure.

Referring to FIG. 2, a magnetic device 2 includes a conductive layer 10into which current is injected in a first direction (x axis direction)and which cause spin Hall effect or Rashba effect, a ferromagnetic layer20 which is disposed in contact with the conductive layer 10 such thatthe ferromagnetic layer 20 and the conductive layer 10 are staked oneach other and whose magnetization direction is switched, and a spinfilter structure 11 which has a fixed magnetization direction and isdisposed on at least one of opposite side surfaces of the firstdirection (x axis direction) of the conductive layer 10 to injectspin-polarized current into the conductive layer 10. Spin polarization(SP) of the spin filter structure 11 may be greater than 0 and equal toor smaller than 1. The spin filter structure 11 may be a half-metallicferromagnet.

The conductive layer 10 and the ferromagnetic layer 20 are stacked oneach other, and the conductive layer 10 extends in the x axis direction(first direction) and has first-direction width and thickness. Theconductive layer 10 and the ferromagnetic layer 20 may be aligned in avertical (z axis) direction. The spin filter structure 11 having aferromagnetism of a fixed magnetic direction is disposed at one end ofthe x axis direction of the conductive layer 10. The magnetizationdirection of the spin filter structure 11 may be a y axis direction. Alength of the spin filter structure 11 is L. A thickness of the spinfilter structure 11 may be equal to that of the conductive layer 10.Current flows in the x axis direction, and the z axis direction is athickness direction of the ferromagnetic layer 20. An interface betweenthe conductive layer 10 and the ferromagnetic layer 20 is z=0. A widthand a thickness of the first direction of the conductive layer 10 are wand t_(N), respectively. A width and a thickness of the first directionof the ferromagnetic layer 20 are w and t_(F), respectively. Theconductive layer 10 may receive spin-polarized current aligned in themagnetization direction of the spin filter structure by the spin filterstructure.

The conductive layer 10 may cause spin Hall effect or Rashba effect. Theconductive layer 10 may include a non-magnetic metal or a half-metallicmaterial. The non-magnetic metal may cause spin Hall effect and may betungsten (W), tantalum (Ta) or platinum (Pt). The half-metallic materialmay cause spin Hall effect and may be PtMn, IrMn or FeMn.

For example, the spin-polarized current of the y axis direction maygenerate spin Hall effect by impurity scattering of the conductive layer10 to provide electrons aligned along y axis to a top surface of theconductive layer 10 and to provide electrons aligned along −y axis to abottom surface of the conductive layer 10. Spin accumulation disposed onthe top surface of the conductive layer 10 may cause a spin-orbit torqueto reverse the magnetization direction of the ferromagnetic layer 20.

An auxiliary conductive layer may be connected to the spin filterstructure to supply current to the spin filter structure. The auxiliaryconductive layer may be a material having a higher electric conductivitythan the conductive layer 10.

The ferromagnetic layer 20 may include a ferromagnet having a switchedmagnetization direction. The ferromagnetic layer 20 may include at leastone of Fe, Co, Ni, and Gd. The ferromagnetic layer 20 may a multilayerthin film including a combination thereof. The ferromagnetic layer 20may include CoFeB. The ferromagnetic layer 20 may be magnetized in anout-of-plane direction having perpendicular magnetic anisotropy.

The spin filter structure 11 may be a half-metallic ferromagnet. Thehalf-metallic ferromagnet may include at least one of a Heusler alloy,magnetite (Fe₃O₄), and lanthanum strontium manganite (LSMO). The spinfilter structure 11 may be a half metal whose spin polarization is equalto 1 (SP=1). When the spin filter structure 11 has one spin state at anenergy level of a half metal while a majority band and a minority bandare separated from each other, the spin filter structure 11 is aconductor in which electrons flow smoothly. However, when the spinfilter structure 11 has an opposite pin state, the spin filter hasnonconductor or semiconductor characteristics.

Examples of the half-metallic ferromagnet are materials such as Heusleralloy, magnetite (Fe₃O₄) and alloy, and lanthanum strontium manganite(LSMO) and alloy. Examples of the Heusler alloy are as follows:

Cu₂MnAl, Cu₂MnIn, Cu₂MnSn,

Ni₂MnAl, Ni₂MnIn, Ni₂MnSn, Ni₂MnSb, Ni₂MnGa

Co₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Co₂NiGa

Pd₂MnAl, Pd₂MnIn, Pd₂MnSn, Pd₂MnSb

Co₂FeSi, Co₂FeAl

Fe₂Val

Mn₂VGa, Co₂FeGe

The spin filter structure 11 may be a ferromagnet whose spinpolarization is greater than 0.5 (SP>0.5). Spin splitting efficiency mayincrease in proportion to a value of the spin polarization (SP). Thespin filter structure 11 may include a ferromagnet, and a magnetizationdirection of the spin filter structure 11 may be perpendicular (y axisdirection) to an extending direction (y axis direction) of thenon-magnetic layer. Accordingly, the spin filter structure 11 mayreceive in-plane current to provide electrons having a spin direction ofthe y axis direction.

[Model Calculation Method]

First, we calculate spin accumulation with respect to an SF/NMstructure. The “SF” represents the spin filter structure 11, and the“NM” represents a non-magnetic layer or the conductive layer 10. In thiscalculation, the magnetic layer 20 was neglected (interface scatteringwas neglected at an SF/NM interface). If a spin filter drift-diffusionequation is solved to the SF/NM interface, we can obtain a y-element ofspin accumulation at the non-magnetic layer.

$\begin{matrix}{{\mu_{y}^{s}(x)} = {\beta\;{el}_{sf}^{F}\frac{\rho_{F}{\exp\left( {{- x}/l_{sf}^{N}} \right)}}{\rho_{F} + {\rho_{N}{\coth\left( {{L/2}l_{sf}^{F}} \right)}}}E_{x}}} & {{Equation}\mspace{14mu}(1)}\end{matrix}$

In the Equation (1), ρ_(F) represents a resistivity of a spin filterstructure (SF) having a fixed magnetization direction, ρ_(N) representsa resistivity of a non-magnetic layer NM, L represents a length of thespin filter structure, f_(sf) and l_(sf) ^(N) represent spin-flipdiffusion lengths of the spin filter structure 11 formed of aferromagnet and the non-magnetic layer NM, respectively, E_(x)represents an electric field applied in an x axis direction, andβ(0<β≤1) represents a spin polarization of the spin filter structure 11.For the reference, x=0 is selected as an interface of spin filterstructure/non-magnetic metal layer.

Next, we concentrate on an NM/FM structure. The NM represents anon-magnetic layer, and the FM represents a ferromagnetic layer. When weapply an external electric field in the x axis direction, charge andspin current densities flowing in z axis direction are given as follows.

$\begin{matrix}{{j_{z} = {{\frac{\sigma}{e}{\partial_{z}\overset{\_}{\mu}}} - {\frac{\sigma_{SH}}{e}ɛ_{ij}{\partial_{i}\mu_{j}^{s}}\mspace{14mu}{and}}}}{j_{i,z}^{s} = {{\frac{\sigma}{e}{\partial_{z}\mu_{j}^{s}}} + {\frac{\sigma_{SH}}{e}ɛ_{ij}{{\partial_{j}\overset{\_}{\mu}}.}}}}} & {{Equation}\mspace{14mu}(2)}\end{matrix}$

In the Equation (2), i and j represent components of a coordinatesystem, respectively, σ represents an electric conductivity, erepresents charge amount of electron, μ represents an electrochemicalpotential, μ_(j) ^(s) represents j-component spin accumulation having apolarization direction, σ_(SH) a spin Hall electric conductivity of thenon-conductivity, and ε_(ij) represents a Levi-Civita symbol usedusually in mathematics and physics.

For clarity, we make it clear in advance that the definition of spincurrent of the Equation (2) is different from a conventional definitionQ_(i,z) ^(s)=−(ℏ/2e)j_(i,z) ^(s) by a constant multiple. Subscripts iand z denote spin polarization direction and flow direction of the spincurrent, respectively. With respect to the ferromagnetic layer 20, anequation for charge and spin current is given as follows.

$\begin{matrix}{{j_{z} = {{\frac{\sigma}{e}{\partial_{z}\overset{\_}{\mu}}} + {\beta_{0}{\hat{M} \cdot {\partial_{z}\mu^{s}}}\mspace{14mu}{and}}}}{j_{i,z}^{s} = {{\frac{\sigma}{e}\beta_{0}{\hat{M}}_{i}{\partial_{z}\overset{\_}{\mu}}} + {\frac{\sigma_{SH}}{e}{\partial_{z}\mu_{l}^{s}}}}}} & {{Equation}\mspace{14mu}(3)}\end{matrix}$

In the Equation (3), M{circumflex over ( )} represents a unit vectoralong the magnetization and β₀ represents spin polarization of theferromagnetic layer 20.

The spin filter structure 11 provides additional spin accumulation tothe non-magnetic layer. The spin accumulation decreases exponentially inthe x axis direction. It is difficult to obtain an analytical solutionto a two-dimensional spin diffusion equation. Accordingly, weapproximately obtain ansatz with respect to the spin accumulation fromthe non-magnetic layer NM by simply adding average spin accumulationfrom the spin filter structure 11 to a value of diffusion equation inthe z axis direction.μ_(i) ^(s)(x,z)=A _(i) exp(z/l _(sf) ^(N))+B exp(−z/l _(sf)^(N))+K,  Equation (4)

We use an approximation, as follows.

$K = {\frac{\beta\;{eE}_{z}l_{sf}^{F}\rho_{F}}{\rho_{F} + {\rho_{N}{\coth\left( {{L/2}\; l_{sf}^{F}} \right)}}}\frac{1}{w}{\int_{0}^{x}{{dx}\;{\exp\left( {{- x}/l_{sf}^{N}} \right)}}}}$

In the equation above, w represents a width of the non-magnetic layerand we obtain j_(z)=(σ/e)∂_(z) μ from the equations (2) and (4). Weassume that a sample is infinite in the y axis direction and thin enoughin the z axis direction. In the case of a normal state (j_(x)=constant,j_(z)=0), a continuity equation ∇·j=∂_(z)j_(z)=0 induces ∂_(z) ² μ=0. Avalue of this equation is μ=Cz+F(x), where C represents a constant andF(x) represents external electric field contribution (F(x)˜θE_(x)x). Inthe case that current flowing in the z axis direction is zero (j_(z)=0),the current is given as follows.

$\begin{matrix}{{\int{j_{z}{dz}}} = {{\frac{\sigma}{e}\overset{\_}{\mu}} = G}} & {{Equation}\mspace{14mu}(5)}\end{matrix}$

The above equation is expressed as follows.μ=eE _(x) x  Equation (6)

If the equations (2), (4), and (6) are used, we obtain the followingequation.

$\begin{matrix}{j_{i,z}^{s} = {{\frac{\sigma}{{el}_{sf}}\left( {{A_{i}{\exp\left( {z/l_{sf}^{N}} \right)}} + {B_{i}{\exp\left( {{- z}/l_{sf}^{N}} \right)}}} \right)} + {\sigma_{SH}E_{x}\delta_{i,y}}}} & {{Equation}\mspace{14mu}(7)}\end{matrix}$

At the NM/FM interface, charge and spin current are given as follows.

$\begin{matrix}{{j_{z} = {{\left( {G_{\uparrow} + G_{\downarrow}} \right)\left( {\Delta\;{\overset{\_}{\mu}/e}} \right)} + {\left( {G_{\uparrow} - G_{\downarrow}} \right)\left( {{\hat{M} \cdot \Delta}\;{\mu_{s}/e}} \right)}}},{\left( \int_{z}^{s} \right)_{T} = {- {\frac{1}{e}\left\lbrack {{\frac{{Re}\left( G_{\uparrow \downarrow} \right)}{e}\left( {2\;\Delta\;\mu_{s} \times \hat{M}} \right) \times \hat{M}} + {\frac{{Im}\left( G_{\uparrow \downarrow} \right)}{e}\left( {2\;\Delta\;\mu_{s} \times \hat{M}} \right)}} \right\rbrack}}},{\left( \int_{z}^{s} \right)_{L} = {\frac{1}{e}\left\lbrack {{\left( {G_{\uparrow} + G_{\downarrow}} \right){\hat{M} \cdot \Delta}\;\mu_{s}} + {\left( {G_{\uparrow} - G_{\downarrow}} \right)\Delta\;\overset{\_}{\mu}}} \right\rbrack}},} & {{Equation}\mspace{14mu}(8)}\end{matrix}$

In the equation (8), subscripts T and L represent a transversalcomponent and a longitudinal component, respectively, G_(↑)(G_(↓))represents an interface conductivity of a majority (minority) spin, andG_(↑↓) represents a spin mixing conductance.

Also, in the equation (8), Δμ(Δμ_(s)) represents a charge (spin)chemical potential drop. We assume that a spin dephasing length is veryshort at the ferromagnetic layer and thus perpendicular spin current(j_(z) ^(s))_(T) is completely absorbed at the NM/FM interface. As aresult, the spin torque is described as follows.

$\begin{matrix}{\frac{\partial M}{\partial t} = {{- \frac{\hslash}{2e}}\frac{\gamma}{\mu_{0}M_{s}t_{F}}\left( {0 - j_{z}^{s}} \right)_{T}}} & {{Equation}\mspace{14mu}(9)}\end{matrix}$

In the equation (9), γ represents a gyromagnetic ratio and M_(s)represents a magnetization per unit volume. The spin torque is describedas a damping like torque and a field-like torque.

$\begin{matrix}{\frac{\partial\hat{M}}{\partial t} = {{{- T_{D}}\hat{M} \times \left( {\hat{M} \times \hat{y}} \right)} - {T_{F}\hat{M} \times \hat{y}}}} & {{Equation}\mspace{14mu}(10)}\end{matrix}$

In the equation (10), T_(D)(T_(F)) represents a coefficient of adamping-like (field-like) torque. If the above bulk equation is solvedat a top surface (z=t_(F)) of the ferromagnetic layer and a bottomsurface (z=−t_(N)) of the non-magnetic layer under the interfacecondition (j_(z)=0 and j_(z) ^(s)=0), we obtain equations as follows.

$\begin{matrix}{{{Equation}\mspace{14mu}(11)\mspace{14mu}{and}\mspace{14mu}{Equation}\mspace{14mu}(12)}\mspace{380mu}} & \; \\{T_{D} = {\frac{\hslash}{2e}\frac{\gamma}{\mu_{0}M_{s}t_{F}}\left\{ {{\theta_{SH}\sigma\; E_{x}\frac{\left( {1 -} \right)^{2}}{1 + {e^{{- 2}{t_{N}/l_{d}^{N}}}}}} + {\frac{\sigma}{{el}_{sf}^{N}}K\;{\tanh\left( {t_{N}/l_{sf}^{N}} \right)}}} \right\} \times \frac{{{\overset{\sim}{G}}^{\uparrow \downarrow}}^{2} + {{{Re}\left( {\overset{\sim}{G}}^{\uparrow \downarrow} \right)}{\tanh^{2}\left( {t_{N}/l_{sf}^{N}} \right)}}}{{{\overset{\sim}{G}}^{\uparrow \downarrow}}^{2} + {2\;{{Re}\left( {\overset{\sim}{G}}^{\uparrow \downarrow} \right)}{\tanh^{2}\left( {t_{N}/l_{sf}^{N}} \right)}} + {\tanh^{4}\left( {t_{N}/l_{sf}^{N}} \right)}}}} & (11) \\{and} & \; \\{{T_{F} = {{- \frac{\hslash}{2e}}\frac{\gamma}{\mu_{0}M_{s}t_{F}}\left\{ {{\theta_{SH}\sigma\; E_{x}\frac{\left( {1 -} \right)^{2}}{1 +}} + {\frac{\sigma}{{el}_{sf}^{N}}K\;{\tanh\left( {t_{N}/l_{sf}^{N}} \right)}}} \right\} \times \frac{{{Im}\left( {\overset{\sim}{G}}^{\uparrow \downarrow} \right)}{\tanh^{2}\left( {t_{N}/l_{sf}^{N}} \right)}}{{{\overset{\sim}{G}}^{\uparrow \downarrow}}^{2} + {2\;{{Re}\left( {\overset{\sim}{G}}^{\uparrow \downarrow} \right)}{\tanh^{2}\left( {t_{N}/l_{sf}^{N}} \right)}} + {\tanh^{4}\left( {t_{N}/l_{sf}^{N}} \right)}}}},} & (12) \\\; & \;\end{matrix}$

In the equations (11) and (12), θ_(SH)=σ_(SH)/σ represents the amountdefined as a spin Hall angle and {tilde over (G)}^(↑↓)=G^(↑↓){2l_(sf)^(N) tan h(t_(N)/l_(sf) ^(N))}/σ. Also, in the equations (11) and (12),a spin torque localized at the NM/FM interface is averaged with respectto a thickness of the ferromagnetic layer t_(F). A first term of eachtorque corresponds to a spin Hall contributory portion when the spinHall structure 11 does not exist.

The effect of the spin filter structure is reflected in the second term.Spins are partially polarized at the non-magnetic layer NM by the spinfilter structure 11. Accordingly, even when there is no spin Halleffect, a non-zero spin chemical potential drop is induced at the NM/FMinterface to produce a spin torque. Spin accumulation caused by the spinfilter structure 11 applies a torque to the ferromagnetic layer 20 evenwhen there is no direct current-flow perpendicular to the interface.This type of spin torque was experimentally observed in a non-localgeometry and is a lateral spin torque caused by inhomogeneousmagnetization.

FIG. 3 illustrates position-dependent spin accumulation at the magneticdevice in FIG. 2.

Referring to FIG. 3, the following parameters were used in a simulation.A non-magnetic layer NM is platinum (Pt), and a spin filter structure 11is cobalt (Co).

σ_(F)=5×10⁶ m⁻¹Ω⁻¹, σ_(N)=5×10⁶ m⁻¹Ω⁻¹, l_(sf) ^(F)=38 nm, l_(sf)^(N)=1-10 nm, Re[G^(↑↓)]=5.94×10¹⁴ m⁻²Ω⁻¹, and lm[G^(↑↓)]=0.86×10¹⁴m⁻²Ω⁻¹. An electric field applied to the non-magnetic layer NM isE_(x)=2×10⁴ V/m, and a charge current density in the x direction isapproximately σ_(N)E_(x)≅10¹¹ A/m². The other parameters were selectedas follows. A magnetization of the ferromagnetic layer 10 was M_(s)=1.0MA/m, a length of the spin filter structure 11 was L=20 nm, a spin Hallangle of the non-magnetic layer used θ_(SN)=0-0.9, and a spinpolarization of the spin filter structure 11 used β=0-1.0.

FIG. 3 shows y-component spin accumulation μ_(y) ^(s) in NM of NM(5nm)/FM(1.5 nm) structure with respect to θ_(SH)=0.3. At an upper edge(z=0), the net amount of the spin accumulation increases as spinpolarization β increases. This causes a spin torque to increase in theequations (11) and (12).

FIG. 4 illustrates dependencies of a damping-like spin torque T_(D) onfour parameters θ_(SH), t_(N), l_(sf) ^(N), and w.

Referring to FIG. 4, resulting damping-like spin torques increasesaccording to an increasing spin Hall angle θ_(SH). The damping-like spintorque increases according to a thickness of a non-magnetic layer NMt_(N). The damping-like spin torque exhibits a maximum according to aspin-flip diffusion length l_(sf) ^(N). A spin-flip diffusion length ofthe non-magnetic layer NM may be between 3 and 4 nm.

An additional spin torque from the spin polarization decays in an xdirection. With respect to non-zero spin polarization β, thedamping-like spin torque increases to a width w of the non-magneticlayer NM. The spin polarization increases the damping-like spin torque.

FIG. 5 illustrates dependencies of a field-like spin torque T_(F) onfour parameters θ_(SH), t_(N), l_(sf) ^(N), and w.

Referring to FIG. 5, the field-like spin torque T_(F) is 10 timessmaller than the damping-like spin torque T_(D). This is becauselm[G^(↑↓)] is smaller than Re[G^(↑↓)] in parameterization. Thedependencies of the field-like spin torque on the four parametersθ_(SH), t_(N), l_(sf) ^(N), and w are similar to each other.

FIG. 6 is a conceptual diagram of a magnetic device including a spinfilter structure according to another example embodiment of the presentdisclosure.

Referring to FIG. 6, a magnetic device 3 includes a conductive layer 10into which current is injected in a first direction and which cause spinHall effect or Rashba effect, a ferromagnetic layer 20 which is disposedin contact with the conductive layer 10 such that the ferromagneticlayer 20 and the conductive layer 10 are staked on each other and whosemagnetization direction is switched, and a spin filter structure 11which has a fixed magnetization direction and is disposed on at leastone of opposite side surfaces of the first direction of the conductivelayer 10 to inject spin-polarized current into the conductive layer 10.

A magnetization direction of the spin filter structure 11 may be adirection (z axis direction) perpendicular to a plane on which theconductive layer 10 is disposed. A magnetization direction of theferromagnetic layer 20 may be an out-of-plane direction havingperpendicular magnetization anisotropy.

A spin polarization of the spin filter structure 11 may be between 0.5and 1. The spin filter structure 11 may be half-metallic ferromagnet.The half-metallic ferromagnet may include at least one of a Heusleralloy, magnetite (Fe₃O₄), and lanthanum strontium manganite (LSMO). Thespin filter structure 11 may include a ferromagnet, and a magnetizationdirection of the spin filter structure 11 is perpendicular to a plane onwhich the conductive layer 10 is disposed. When the magnetizationdirection of the spin filter structure 11 is aligned in the z axisdirection, the ferromagnetic layer 20 having perpendicular magneticanisotropy may be deterministically switched without an externalmagnetic field by a spin polarization flowing to the conductive layer10.

FIG. 7 illustrates a magnetic device according to another exampleembodiment of the present disclosure.

Referring to FIG. 7, a magnetic device 4 includes a conductive layer 10into which current is injected in a first direction and which cause spinHall effect or Rashba effect, a ferromagnetic layer 20 which is disposedin contact with the conductive layer 10 such that the ferromagneticlayer 20 and the conductive layer 10 are staked on each other and whosemagnetization direction is switched, and a spin filter structure 11which has a fixed magnetization direction and is disposed on at leastone of the opposite side surfaces of the first direction of theconductive layer 10 to inject spin-polarized current into the conductivelayer 10.

The spin filter structure 11 may be disposed at opposite side surfacesof the first direction of the non-magnetic layer 10. A magnetizationdirection (+y axis direction) of the spin filter structure 11 disposedleft may be −y axis direction to be antiparallel to a magnetizationdirection of the spin filter structure 11 disposed right. Accordingly,spin accumulation of y axis direction may have a symmetrical (even)function form. The spin accumulation of y axis direction caused by thespin-polarized current provides a spin torque to the ferromagnetic layer20. In addition, the ferromagnetic layer 20 having perpendicularmagnetic anisotropy may cause spin accumulation aligned in the y axisdirection which results from scattering of the spin-polarized current,and y-direction spin accumulation resulting from spin Hall effect mayprovide an additional spin torque to the ferromagnetic layer 20.

FIG. 8 illustrates a magnetic device according to another exampleembodiment of the present disclosure.

Referring to FIG. 8, a magnetic device 5 includes a conductive layer 10into which current is injected in a first direction and which cause spinHall effect or Rashba effect, a ferromagnetic layer 20 which is disposedin contact with the conductive layer 10 such that the ferromagneticlayer 20 and the conductive layer 10 are staked on each other and whosemagnetization direction is switched, and a spin filter structure 11which has a fixed magnetization direction and is disposed on at leastone of opposite side surfaces of the first direction of the conductivelayer 10 to inject spin-polarized current into the conductive layer 10.The spin filter structure 11 may be disposed at opposite side surfacesof the first direction of the non-magnetic layer 10. A magnetizationdirection (+z axis direction) of the spin filter structure 11 disposedleft may be −z axis direction to be antiparallel to a magnetizationdirection of the spin filter structure 11 disposed right. Thus, spinaccumulation of y axis direction may have a symmetrical (even) functionform. When the magnetization direction of the spin filter structure 11is aligned in the z axis direction, the ferromagnetic layer 20 havingperpendicular magnetic anisotropy may be deterministically without anexternal magnetic field by a spin polarization flowing to the conductivelayer 10.

FIG. 9 illustrates a magnetic device according to another exampleembodiment of the present disclosure.

Referring to FIG. 9, a magnetic device 6 includes a conductive layer 10into which current is injected in a first direction and which cause spinHall effect or Rashba effect, a ferromagnetic layer 20 which is disposedin contact with the conductive layer 10 such that the ferromagneticlayer 20 and the conductive layer 10 are staked on each other and whosemagnetization direction is switched, and a spin filter structure 11which has a fixed magnetization direction and is disposed on at leastone of opposite side surfaces of the first direction of the conductivelayer 10 to inject spin-polarized current into the conductive layer 10.A magnetization direction (−x axis direction) of the spin filterstructure 11 disposed left may be +x axis direction to be antiparallelto a magnetization direction of the spin filter structure 11 disposedright. Thus, spin accumulation of x axis direction may have asymmetrical (even) function form. When the magnetization direction ofthe spin filter structure 11 is aligned in the x axis direction, theferromagnetic layer 20 having perpendicular magnetic anisotropy may beprovided with a spin torque by a spin polarization flowing to theconductive layer 10.

FIG. 10 illustrates spin accumulation depending on magnetizationdirections of a spin filter structure and a ferromagnet according toanother example embodiment of the present disclosure.

Referring to FIG. 10, when a ferromagnetic layer has perpendicularmagnetic anisotropy, a magnetization direction of a spin filterstructure may be z axis direction to switch the ferromagnetic layerwithout an external magnetic field (a-2).

In addition, when the ferromagnetic layer has an in-plane magnetizationdirection and a magnetization of the spin filter structure is the sameas that of the ferromagnetic layer, the ferromagnetic layer may beswitched without an external magnetic field (b-1 and c-3).

FIG. 11 illustrates magnetic tunnel devices according to another exampleembodiment of the present disclosure.

Referring to FIG. 11, each of magnetic tunnel junction devices 100 a to100 d includes a magnetic tunnel junction 101 including a pinnedmagnetic layer 140, a free magnetic layer 120, and a tunnel barrierlayer 130 interposed between the pinned magnetic layer 140 and the freemagnetic layer 120, a conductive pattern 110 to which in-plane currentflows and which is disposed adjacent to the free magnetic layer 120 tocause spin Hall effect or Rashba effect to apply a spin torque to thefree magnetic layer 120 of the magnetic tunnel junction 101, and a spinfilter structure 111 disposed on at least one of the opposite sidesurfaces of the conductive pattern 110 in a direction in which thein-plane current is applied. The spin filter structure 111 filters theinjected current to control the amount and direction of a spin andsupplies the filtered current to the conductive pattern 110.

The magnetic tunnel junction devices 100 a to 100 d constitute a portionof a magnetic memory cell. A conductive pattern 110, a free magneticlayer 120, a tunnel barrier layer 130, and a pinned magnetic layer 140are sequentially stacked on a substrate. The pinned magnetic layer 140may be connected to a wiring. The conductive pattern 110 may supplyin-plane current and may cause spin Hall effect or Rashba effect. Thespin filter structure 111 may be disposed on at least one side surfaceof the conductive pattern 110 in a direction in which the in-planecurrent flows. An auxiliary conductive pattern 112 may be connected tothe spin filter structure 111. The in-plane current may flow through theauxiliary conductive pattern 112, the spin filter structure 111, and theconductive pattern 110. The spin filter structure 111 may supplyspin-polarized current to the conductive pattern 110, and the conductivepattern 110 may provide a spin orbit torque to the free magnetic layer120 due to spin Hall effect or Rashba effect to lead to magnetizationreversal. In addition, the spin filter structure 111 may provide spinaccumulation aligned in a magnetization direction of the spin filterstructure 111 and the spin accumulation may provide a deterministicswitching effect or an effect to provide an additional torque.

The free magnetic layer 120 may be aligned perpendicularly to theconductive pattern 110. Alternatively, according to a modifiedembodiment of the present disclosure, the conductive pattern 112 may notbe aligned perpendicularly to the free magnetic layer 120. The spinfilter structure 111 may be disposed to have a portion that is incontact with the free magnetic layer 120 or may be disposed not to havea portion that is in contact with the free magnetic layer 120. The spinfilter structure 111 may be formed by a conventional patterning processto have a corner or may be a sidewall spacer structure formed by aconformal deposition process or an anisotropic etching process.

FIG. 12 illustrates magnetic tunnel devices according to another exampleembodiment of the present disclosure.

Referring to FIG. 12, each of magnetic tunnel junction devices 100 e to100 h includes a magnetic tunnel junction 101 including a pinnedmagnetic layer 140, a free magnetic layer 120, and a tunnel barrierlayer 130 interposed between the pinned magnetic layer 140 and the freemagnetic layer 120, a conductive pattern 110 to which in-plane currentflows and which is disposed adjacent to the free magnetic layer 120 tocause spin Hall effect or Rashba effect to apply a spin torque to thefree magnetic layer 120 of the magnetic tunnel junction 101, and a spinfilter structure 111 disposed on at least one of the opposite sidesurfaces of the conductive pattern 110 in a direction in which thein-plane current is applied. The spin filter structure 111 filters theinjected current to control the amount and direction of a spin andsupplies the filtered current to the conductive pattern 110.

The magnetic tunnel junction devices 100 e to 100 h constitute a portionof a magnetic memory cell. A conductive pattern 110, a free magneticlayer 120, a tunnel barrier layer 130, and a pinned magnetic layer 140are sequentially stacked on a substrate. The pinned magnetic layer 140may be connected to a wiring. The conductive pattern 110 may supplyin-plane current and may cause spin Hall effect or Rashba effect. Thespin filter structure 111 may be disposed on at least one side surfaceof the conductive pattern 110 in a direction in which the in-planecurrent flows. An auxiliary conductive pattern 112 may be connected tothe spin filter structure 111. The in-plane current may flow through theauxiliary conductive pattern 112, the spin filter structure 111, and theconductive pattern 110. The spin filter structure 111 may supplyspin-polarized current to the conductive pattern 110, and the conductivepattern 110 may provide a spin orbit torque to the free magnetic layer120 due to spin Hall effect or Rashba effect to lead to magnetizationreversal. In addition, the spin filter structure 111 may provide spinaccumulation aligned in a magnetization direction of the spin filterstructure 111 and the spin accumulation may provide a deterministicswitching effect or an effect to provide an additional torque.

A side surface of the free magnetic layer 120 may be alignedperpendicularly to a side surface of the conductive pattern 110.Alternatively, according to a modified embodiment of the presentdisclosure, the conductive pattern 112 may not be alignedperpendicularly to the free magnetic layer 120. The spin filterstructure 111 may be disposed to have a portion that is in contact withthe free magnetic layer 120 or may be disposed not to have a portionthat is in contact with the free magnetic layer 120. The spin filterstructure 111 may be formed by a conventional patterning process to havea corner or may be a sidewall spacer structure formed by a conformaldeposition process or an anisotropic etching process.

FIG. 13 is a conceptual diagram of a magnetic tunnel junction deviceaccording to another example embodiment of the present disclosure.

Referring to FIG. 13, a magnetic tunnel junction device 200 includes amagnetic tunnel junction 201 including a pinned magnetic layer 240, afree magnetic layer 120, and a tunnel barrier layer 130 interposedbetween the pinned magnetic layer 240 and the free magnetic layer 120, aconductive pattern 110 which is disposed adjacent to the free magneticlayer 120 to cause spin Hall effect or Rashba effect to apply a spintorque to the free magnetic layer 120 of the magnetic tunnel junction101, and a spin filter structure 111 disposed on at least one of theopposite side surfaces of the conductive pattern 110 in a direction inwhich the in-plane current is applied. The spin filter structure 111filters the injected current to control the amount and direction of aspin and supplies the filtered current to the conductive pattern 110.

The spin filter structure 111 is disposed on at least one of theopposite side surfaces of the conductive pattern 110 in a direction inwhich the in-plane current flows. The spin filter structure 111 filtersinjected current to control the amount and direction of a spin andsupplies the injected current to the conductive pattern 110.

The magnetic layer 240 may be a synthetic antiferromagnetic structureincluding a first pinned magnetic layer 244, a non-magnetic layer 246for a pinned magnetic layer, and a second pinned magnetic layer 248which are sequentially stacked. Each of the first and second pinnedmagnetic layers 244 and 248 may independently include at least one ofFe, Co, Ni, Gd, B, Si, Zr, and a combination thereof. The non-magneticlayer 246 for a pinned magnetic layer may include at least one of Ru,Ta, Cu, Pt, Pd, W, Cr, and a combination thereof.

According to a modified embodiment of the present disclosure, the pinnedmagnetic layer 240 may be an exchange-biased antiferromagnetic structureincluding an antiferromagnetic layer 242, a first pinned magnetic layer244, a non-magnetic layer 246 for a pinned magnetic layer, and a secondpinned magnetic layer 248 which are sequentially stacked. Theantiferromagnetic layer 242 may be formed of a material including atleast one of Ir, Pt, Fe, Mn, and a combination thereof. Each of thefirst pinned magnetic layer 244 and the second pinned magnetic layer 248may be independently formed of a material including at least one of Fe,Co, Ni, Gd, B, Si, Zr, and a combination thereof. The non-magnetic layer246 for a pinned magnetic layer may be formed of a material including atleast one of Ru, Ta, Cu, Pt, Pd, W, Cr, and a combination thereof.

FIG. 14 is a conceptual diagram of a magnetic tunnel junction deviceaccording to another example embodiment of the present disclosure.

Referring to FIG. 14, a magnetic tunnel junction device 300 includes amagnetic tunnel junction 301 including a pinned magnetic layer 140, afree magnetic layer 320, and a tunnel barrier layer 130 interposedbetween the pinned magnetic layer 140 and the free magnetic layer 120, aconductive pattern 110 which is disposed adjacent to the free magneticlayer 120 to cause spin Hall effect or Rashba effect to apply a spintorque to the free magnetic layer 120 of the magnetic tunnel junction101, and a spin filter structure 111 disposed on at least one of theopposite side surfaces of the conductive pattern 110 in a direction inwhich the in-plane current is applied. The spin filter structure 111filters the injected current to control the amount and direction of aspin and supplies the filtered current to the conductive pattern 110.

The pinned magnetic layer 140 and the free magnetic layer 320 may not bealigned with each other. Specifically, the free magnetic layers 320 mayextend parallel to each other in an extending direction of theconductive pattern 110. The free magnetic layer 320 may include at leastone magnetic domain 321. The magnetic domain 321 may be a magnetic wallor a skyrmion and may divide magnetic domains magnetized in oppositedirections.

FIG. 15 is a conceptual diagram of a magnetic tunnel junction deviceaccording to another example embodiment of the present disclosure.

Referring to FIG. 15, a magnetic tunnel junction device 400 includes amagnetic tunnel junction 101 including a pinned magnetic layer 140, afree magnetic layer 120, and a tunnel barrier layer 130 interposedbetween the pinned magnetic layer 140 and the free magnetic layer 120, aconductive pattern 410 which is disposed adjacent to the free magneticlayer 120 to cause spin Hall effect or Rashba effect to apply a spintorque to the free magnetic layer 120 of the magnetic tunnel junction101, and a spin filter structure 111 disposed on at least one of theopposite side surfaces of the conductive pattern 410 in a direction inwhich the in-plane current is applied. The spin filter structure 111filters the injected current to control the amount and direction of aspin and supplies the filtered current to the conductive pattern 410.

The conductive pattern 410 may include a conductive antiferromagnet.Specifically, the conductive pattern 410 may apply the in-plane currentand may include an antiferromagnetic layer. The conductive pattern 410may provide an in-plane exchange-biased magnetic field to the freemagnetic layer 120 having perpendicular magnetic anisotropy.Specifically, the conductive pattern 410 may be PtMn, IrMn or FeMn. Theantiferromagnetic layer may provide an exchange-biased magnetic field tothe free magnetic layer 120. Thus, the magnetic tunnel junction device400 may switch a magnetization direction of the free magnetic layer 120having perpendicular magnetic anisotropy without using an externalmagnetic field.

FIG. 16 is a conceptual diagram of a magnetic tunnel junction deviceaccording to another example embodiment of the present disclosure.

Referring to FIG. 16, a magnetic tunnel junction device 500 includes amagnetic tunnel junction 101 including a pinned magnetic layer 140, afree magnetic layer 120, and a tunnel barrier layer 130 interposedbetween the pinned magnetic layer 140 and the free magnetic layer 120, aconductive pattern 510 which is disposed adjacent to the free magneticlayer 120 to cause spin Hall effect or Rashba effect to apply a spintorque to the free magnetic layer 120 of the magnetic tunnel junction101, and a spin filter structure 111 disposed on at least one of theopposite side surfaces of the conductive pattern 510 in a direction inwhich the in-plane current is applied. The spin filter structure 111filters the injected current to control the amount and direction of aspin and supplies the filtered current to the conductive pattern 510.

The conductive pattern 510 applying the in-plane current may include anantiferromagnetic layer 510 a and a ferromagnetic layer 510 b which aresequentially stacked. The ferromagnetic layer 510 b may have an in-planemagnetization direction or a magnetization direction in which theferromagnetic layer 510 b extends. The antiferromagnetic layer 510 a mayprovide an in-plane exchange-biased magnetic field to the free magneticfield 120. The free magnetic field 120 may be switched without using anexternal magnetic field.

The ferromagnetic layer 510 b has in-plane magnetic anisotropy andprovides a function to antiferromagnetically align the antiferromagneticlayer 510 a in an in-plane direction. The antiferromagnetic layer 510 aadjacent to the free magnetic layer 120 having perpendicular magneticanisotropy establishes an exchange-biased magnetic field in a directionhorizontal to the free magnetic layer 120 having perpendicular magneticanisotropy. Specifically, the antiferromagnetic layer 510 a isantiferromagnetically aligned in the in-plane direction by an exchangeinteraction between the ferromagnetic layer 510 b having in-planeanisotropy and the antiferromagnetic layer 510 a during thermalannealing under a horizontal magnetic field. Thus, an exchange-biasedmagnetic field of a horizontal direction is induced at the free magneticfield 120 having perpendicular magnetic anisotropy adjacent to anotherside by an antiferromagnetic rule. Current flowing to the conductivepattern 510 including the antiferromagnetic layer 510 a generates aspin-orbit torque through anomalous Hall effect or spin Hall effect. Thespin filter structure 111 may be disposed only on a side surface of theantiferromagnetic layer 510 a.

FIG. 17 is a conceptual diagram of a magnetic tunnel junction deviceaccording to another example embodiment of the present disclosure.

Referring to FIG. 17, a magnetic tunnel junction device 600 includes amagnetic tunnel junction 101 including a pinned magnetic layer 140, afree magnetic layer 120, and a tunnel barrier layer 130 interposedbetween the pinned magnetic layer 140 and the free magnetic layer 120, aconductive pattern 110 which is disposed adjacent to the free magneticlayer 120 to cause spin Hall effect or Rashba effect to apply a spintorque to the free magnetic layer 120 of the magnetic tunnel junction101, and a spin filter structure 111 disposed on at least one of theopposite side surfaces of the conductive pattern 110 in a direction inwhich the in-plane current is applied. The spin filter structure 111filters the injected current to control the amount and direction of aspin and supplies the filtered current to the conductive pattern 110.

A dipole field non-magnetic layer 652 and a dipole field ferromagneticlayer 654 having an in-plane magnetization direction are sequentiallystacked adjacent to the pinned magnetic layer 140. The dipole fieldnon-magnetic layer 652 is disposed adjacent to the pinned magnetic layer140.

The dipole field non-magnetic layer 652 may include at least one of Ru,Ta, Cu, Pt, Pd, W, Cr, and a combination thereof.

The dipole field ferromagnetic layer 654 may have an in-planemagnetization direction (e.g., −x axis direction) and may establish adipole magnetic field to establish a magnetic field in the free magneticfield 120 in an in-plane direction (+x axis direction). Thus, themagnetic tunnel junction device 600 may perform magnetization reversalwithout using an external magnetic field.

FIG. 18 is a conceptual diagram of a magnetic tunnel junction deviceaccording to another example embodiment of the present disclosure.

Referring to FIG. 18, a magnetic tunnel junction device 700 includes amagnetic tunnel junction 701 including a pinned magnetic layer 140, afree magnetic layer 120, and a tunnel barrier layer 130 interposedbetween the pinned magnetic layer 140 and the free magnetic layer 120, aconductive pattern 110 which is disposed adjacent to the free magneticlayer 120 to cause spin Hall effect or Rashba effect to apply a spintorque to the free magnetic layer 120 of the magnetic tunnel junction101, and a spin filter structure 111 disposed on at least one of theopposite side surfaces of the conductive pattern 110 in a direction inwhich the in-plane current is applied. The spin filter structure 111filters the injected current to control the amount and direction of aspin and supplies the filtered current to the conductive pattern 110.

An auxiliary insulating layer 727 may be disposed between the conductivepattern 110 and the free magnetic layer 120. The auxiliary insulatinglayer 727 may include at least one of AlO_(x), MgO, TaO_(x), ZrO_(x),and a combination thereof. The auxiliary insulating layer 727 mayprevent in-plane charge current flowing along the conductive pattern 110from flowing directly through the magnetic tunnel junction 701 and mayallow only pure spin current to pass through the magnetic tunneljunction 701.

FIG. 19 is a conceptual diagram of a magnetic tunnel junction deviceaccording to another example embodiment of the present disclosure.

Referring to FIG. 19, a magnetic tunnel junction device 800 includes amagnetic tunnel junction 101 including a pinned magnetic layer 140, afree magnetic layer 120, and a tunnel barrier layer 130 interposedbetween the pinned magnetic layer 140 and the free magnetic layer 120, aconductive pattern 810 which is disposed adjacent to the free magneticlayer 120 to cause spin Hall effect or Rashba effect to apply a spintorque to the free magnetic layer 120 of the magnetic tunnel junction101, and a spin filter structure 111 disposed on at least one of theopposite side surfaces of the conductive pattern 810 in a direction inwhich the in-plane current is applied. The spin filter structure 111filters the injected current to control the amount and direction of aspin and supplies the filtered current to the conductive pattern 810.

The conductive pattern 810 may include a conductive non-magnetic layer810 a and a conducting wire ferromagnetic layer 810 b which aresequentially stacked. The conducting wire ferromagnetic layer 810 b mayinclude an in-plane magnetization direction component. The conductingwire non-magnetic layer 810 a may be disposed adjacent to the freemagnetic layer 120. The conducting wire non-magnetic layer 810 a may beone selected from the group consisting of Cu, Ta, Pt, W, Bi, Ir, Mn, Ti,Cr, Pd, Re, Os, Hf, Mo, Ru, and a combination thereof. The conductingwire ferromagnetic layer 810 b may include at least one of Fe, Co, Ni,B, Si, Zr, and a combination thereof. Spin current may be generatedthrough internal anomalous Hall effect or anisotropic magnetoresistanceeffect of the conducting wire ferromagnetic layer 810 b by in-planecharge current flowing through the conducting wire ferromagnetic layer810 b [T. Taniguchi, J. Grollier, M. D. Stiles, Physical Review Applied3, 044001 (2015)]. Alternatively, spin current may be generated byinterface spin-orbit coupling effect of the conducting wireferromagnetic layer 810 b and the conducting wire non-magnetic layer 810a [V. P. Amin, M. D. Stiles, Physical Review B 94, 104419 (2016)]. Thespin filter structure 111 may be disposed on at least one of theopposite sides of the conducting wire non-magnetic layer 810 a.

FIG. 20 is a conceptual diagram of a magnetic tunnel junction deviceaccording to another example embodiment of the present disclosure.

Referring to FIG. 20, a magnetic tunnel junction device 900 includes amagnetic tunnel junction 901 including a pinned magnetic layer 140, afree magnetic layer 120, and a tunnel barrier layer 130 interposedbetween the pinned magnetic layer 140 and the free magnetic layer 120, aconductive pattern 910 which is disposed adjacent to the free magneticlayer 120 to cause spin Hall effect or Rashba effect to apply a spintorque to the free magnetic layer 120 of the magnetic tunnel junction101, and a spin filter structure 111 disposed on at least one of theopposite side surfaces of the conductive pattern 910 in a direction inwhich the in-plane current is applied. The spin filter structure 111filters the injected current to control the amount and direction of aspin and supplies the filtered current to the conductive pattern 910.

The conductive pattern 910 may include a conducting wire ferromagneticlayer 910 a and a conducting wire non-magnetic layer 910 b which aresequentially stacked. A non-magnetic layer 927 may be provided betweenthe conducting wire ferromagnetic layer 910 a and the free magneticlayer 120. The conducting wire ferromagnetic layer 910 a may be disposedadjacent to the free magnetic layer 120. The non-magnetic layer 927 maybe aligned with a side surface of the free magnetic layer 120.

The conducting wire non-magnetic layer 910 b and the non-magnetic layer927 may be one selected from the group consisting of Cu, Ta, Pt, W, Bi,Ir, Mn, Ti, Cr, Pd, Re, Os, Hf, Mo, Ru, and a combination thereof. Theconducting wire ferromagnetic layer 910 a may include at least one ofFe, Co, Ni, Gd, B, Si, Zr, and a combination thereof. The spin filterstructure 111 may be disposed on at least one of the opposite sidesurfaces of the conducting wire non-magnetic layer 910 b.

FIG. 21 illustrates a magnetic memory device according to anotherexample embodiment of the present disclosure.

Referring to FIG. 21, a magnetic memory device 91 includes a pluralityof magnetic tunnel junctions 101. The magnetic tunnel junction 101 orthe magnetic tunnel junction device 100 may be variously modified, asdescribed with reference to FIGS. 2 to 14.

The magnetic memory device 91 includes a plurality of magnetic tunneljunctions 101 arranged in a matrix format, a first conductive pattern110 disposed adjacent to a free magnetic layer 120 of the magnetictunnel junction 101, and a spin filter structure 111 disposed on atleast one of the opposite side surfaces of the first conductive pattern110. The first conductive pattern 110 provides a spin-orbit torque (SOT)caused by a spin-orbit coupling force between the free magnetic layer120 and the first conductive pattern 110, and the spin filter structure111 provides spin-polarized current to the first conductive pattern 110.

The first conductive pattern 110 may be formed of one selected from thegroup consisting of Cu, Ta, Pt, W, Bi, Ir, Mn, Ti, Cr, Pd, Re, Os, Hf,Mo, Ru, and a combination thereof. The first conductive pattern 110 maysupply spin current to the free magnetic layer 120 and may apply aspin-orbit torque to the free magnetic layer 120. The spin-orbit torquemay contribute to magnetization reversal of the free magnetic layer 120.

The first conductive layers 110 may extend parallel to each other on asubstrate plane in a first direction. A free magnetic layer of each ofthe magnetic tunnel junctions 101 arranged in the first direction may beperiodically disposed adjacent to the first conductive pattern 110. Asecond conductive pattern 182 or WL may be electrically connected to apinned magnetic layer 140 of each of the magnetic tunnel junctions 101arranged in a second direction perpendicular to the first direction andmay extend on the substrate plane in the second direction.

The magnetic memory device 91 may operate as a cross-point memory. Themagnetic memory device 91 may operate due to spin-polarized currentflowing to the first conductive pattern 110, spin Hall effect caused bythe spin-polarized current, and critical current reduction effect causedby a voltage applied to the second conductive pattern 182.Alternatively, the magnetic memory device 91 may operate due tospin-polarized current generated by current flowing to the firstconductive pattern 110, spin Hall effect caused by the spin-polarizedcurrent, and spin-transfer torque effect flowing through a selectedmagnetic tunnel junction.

FIG. 22 illustrates a magnetic memory device according to anotherexample embodiment of the present disclosure.

Referring to FIG. 22, a magnetic memory device 92 includes a pluralityof magnetic tunnel junctions. The magnetic memory device 92 includes aplurality of magnetic tunnel junctions 101 arranged in a matrix format,a first conductive pattern 110 disposed adjacent to a free magneticlayer 120 of the magnetic tunnel junction 101, and a spin filterstructure 111 disposed on at least one of the opposite side surfaces ofthe first conductive pattern 110. The first conductive pattern 110provides a spin-orbit torque (SOT) caused by a spin-orbit coupling forcebetween the free magnetic layer 120 and the first conductive pattern110, and the spin filter structure 111 supplies spin-polarized currentto the first conductive pattern 110.

The first conductive pattern 110 may be periodically disposed to bespaced apart from each other on a substrate plane in a first direction.A free magnetic layer 120 of each of the magnetic tunnel junctionsarranged in the first direction may be periodically disposed adjacent tothe first conductive pattern 110. The first conductive pattern 110 maysupply spin current to the free magnetic layer 120 and may apply aspin-orbit torque to the free magnetic layer 120. The spin-orbit torquemay contribute to magnetization reversal of the free magnetic layer 120.The spin filter structure 111 may supply spin-polarized current to thefirst conductive pattern 110.

A second conductive pattern 282 or WL is electrically connected to thepinned magnetic layer 140 of each of the magnetic tunnel junctionsarranged in the first direction and extends on the substrate plane inthe first direction.

A third conductive layer 283 or SL is connected to one end of each ofthe first conductive patterns 110 arranged in the first direction andextends in the first direction.

A fourth conductive pattern 284 or BL is connected to the other end ofeach of the first conductive patterns 110 arranged in the seconddirection and extends in the second direction.

The magnetic memory device 92 may operate as a modified cross-pointmemory. The first conductive patterns 110 may be divided into each otherto inject spin current into the free magnetic layer 120. When currentflows through the third conductive pattern 283, the first conductivepattern 110, and the fourth conductive pattern 284, in-plane currentflowing to the first conductive pattern 110 may contribute tomagnetization reversal of the free magnetic layer 120 by injecting spincurrent into the free magnetic layer 120.

FIG. 23 illustrates a magnetic memory device according to anotherexample embodiment of the present disclosure.

Referring to FIG. 23, a magnetic memory device 93 includes a pluralityof magnetic tunnel junctions. The magnetic memory device 93 includes aplurality of magnetic tunnel junctions 101 arranged in a matrix format,a first conductive pattern 110 disposed adjacent to a free magneticlayer 120 of the magnetic tunnel junction 101, and a spin filterstructure 111 disposed on at least one of the opposite side surfaces ofthe first conductive pattern 110. The first conductive pattern 110provides a spin-orbit torque (SOT) caused by a spin-orbit coupling forcebetween the free magnetic layer 120 and the first conductive pattern110, and the spin filter structure 111 supplies spin-polarized currentto the first conductive pattern 110.

The first conductive pattern 110 may extend on a substrate plane in afirst direction, and a free magnetic layer 120 of each of the magnetictunnel junctions arranged in the first direction may be periodicallydisposed adjacent to the first conductive pattern 110 or BL. The firstconductive pattern 110 may supply spin current to the free magneticlayer 120 and may apply spin-orbit torque to the free magnetic layer120. The spin-orbit torque may contribute to magnetization reversal ofthe free magnetic layer 120. The spin filter structure 111 may beperiodically disposed at the first conductive pattern 110.

Selection transistors TR may be electrically connected to pinnedmagnetic layers 140 of the magnetic tunnel junctions 101, respectively.

A second conductive pattern 382 or SL may be electrically connected tosource/drain of each of the selection transistors arranged in the firstdirection and may extend on the substrate plane in the first direction.

A third conductive pattern 383 or WL may be connected to a gate of eachof the selection transistors TR arranged in a second directionperpendicular to the first direction.

When current flows to a specific first conductive pattern 110 (BLO),free magnetic layers of all magnetic tunnel junctions connected to thefirst conductive pattern 110 may receive spin current. On the otherhand, a voltage is applied to a specific third conductive patternconnected to a gate of the selection transistor TR to select a specificmemory cell. Thus, the specific memory cell may be provided with avoltage or spin-transfer current to a pinned magnetic layer by spincurrent generated by the first conductive pattern or a selectedselection transistor TR. As a result, a specific memory cell may performa write operation.

FIG. 24 illustrates a magnetic memory device according to anotherexample embodiment of the present disclosure.

Referring to FIG. 24, a magnetic memory device 94 includes a pluralityof magnetic tunnel junctions. The magnetic memory device 94 includes aplurality of magnetic tunnel junctions 101 arranged in a matrix format,a first conductive pattern 110 disposed adjacent to a free magneticlayer 120 of the magnetic tunnel junction 101, and a spin filterstructure 111 disposed on at least one of the opposite side surfaces ofthe first conductive pattern 110. The first conductive pattern 110provides a spin-orbit torque (SOT) caused by a spin-orbit coupling forcebetween the free magnetic layer 120 and the first conductive pattern110, and the spin filter structure 111 supplies spin-polarized currentto the first conductive pattern 110.

The first conductive pattern 110 or WBL may extend on a substrate planein a first direction, and a magnetic free layer 120 of each of themagnetic tunnel junctions arranged in the first direction may beperiodically disposed adjacent to the first conductive pattern 110. Thefirst conductive pattern 110 may supply spin current to the freemagnetic layer 120 and may apply a spin-orbit torque to the freemagnetic layer 120. The spin-orbit torque may contribute tomagnetization reversal of the free magnetic layer 120. The spin filterstructure may be periodically disposed on opposite sides of the firstconductive pattern 110.

Selection transistors TR may be electrically connected to pinnedmagnetic layers 140 of the magnetic tunnel junctions, respectively.

The second conductive patterns 482 or RBL may be electrically connectedto source/drain of each of the selection transistors TR arranged in asecond direction perpendicular to the first direction and may extend onthe substrate plane in the second direction.

A third conductive pattern 483 or WL may be connected to a gate of eachof the selection transistors TR arranged in the first direction.

To perform a write operation on a specific memory cell, a specific firstconductive pattern is selected and current flows to the selected firstconductive pattern. In addition, a third conductive patterns connectedto a gate of a selection transistor TR connected to the selected memorycell is selected and thus a voltage is applied to the pinned magneticlayer or spin-transfer current flows to the pinned magnetic layer. As aresult, the specific memory cell may perform a write operation.

FIG. 25 illustrates a magnetic memory device according to anotherexample embodiment of the present disclosure.

Referring to FIG. 25, a magnetic memory device 95 includes a pluralityof magnetic tunnel junctions. The magnetic memory device 95 includes aplurality of magnetic tunnel junctions 101 arranged in a matrix format,a first conductive pattern 110 disposed adjacent to a free magneticlayer 120 of the magnetic tunnel junction 101, and a spin filterstructure 111 disposed on at least one of the opposite side surfaces ofthe first conductive pattern 110. The first conductive pattern 110provides a spin-orbit torque (SOT) caused by a spin-orbit coupling forcebetween the free magnetic layer 120 and the first conductive pattern110, and the spin filter structure 111 supplies spin-polarized currentto the first conductive pattern 110.

The first conductive pattern 110 may be periodically disposed on asubstrate plane in a first direction, and a magnetic free layer 120 ofeach of the magnetic tunnel junctions arranged in the first directionmay be periodically disposed adjacent to the first conductive pattern110. The first conductive pattern 110 may supply spin current to thefree magnetic layer 120 and may apply a spin-orbit torque to the freemagnetic layer 120. The spin-orbit torque may contribute tomagnetization reversal of the free magnetic layer 120. The spin filterstructure 111 may be disposed on at least one side of the firstconductive pattern 110.

The second conductive patterns 582 or RBL may be electrically connectedto a pinned magnetic layer 140 of each of the magnetic tunnel junctionsarranged in the first direction and may extend in the first direction.

A third conductive pattern 583 or WBL may be connected to one end ofeach of the first conductive patterns 110 arranged in the firstdirection and may extend in the first direction.

Selection transistors TR may be connected to the other end of the firstconductive pattern 110.

A fourth conductive pattern 584 or SL may be connected to source/drainof the selection transistors TR arranged in the first direction and mayextend in the first direction.

A fifth conductive pattern 585 or WL may be connected to a gate of theselection transistors TR arranged in a second direction perpendicular tothe first direction and may extend in the second direction.

FIG. 26 illustrates a magnetic memory device according to anotherexample embodiment of the present disclosure.

Referring to FIG. 26, a magnetic memory device 96 includes a pluralityof magnetic tunnel junctions. The magnetic memory device 96 includes aplurality of magnetic tunnel junctions 101 arranged in a matrix format,a first conductive pattern 110 disposed adjacent to a free magneticlayer 120 of the magnetic tunnel junction 101, and a spin filterstructure 111 disposed on at least one of the opposite side surfaces ofthe first conductive pattern 110. The first conductive pattern 110provides a spin-orbit torque (SOT) caused by a spin-orbit coupling forcebetween the free magnetic layer 120 and the first conductive pattern110, and the spin filter structure 111 supplies spin-polarized currentto the first conductive pattern 110.

The first conductive pattern 110 may be periodically disposed on asubstrate plane in a first direction, and a magnetic free layer 120 ofeach of the magnetic tunnel junctions arranged in the first directionmay be periodically disposed adjacent to the first conductive pattern110. The first conductive pattern 110 may supply spin current to thefree magnetic layer 120 and may apply a spin-orbit torque to the freemagnetic layer 120. The spin-orbit torque may contribute tomagnetization reversal of the free magnetic layer 120. The spin filterstructure 111 may be disposed on at least one side of the firstconductive pattern 110.

Selection transistors TR may be connected to pinned ferromagnetic layers140 of the magnetic tunnel junctions, respectively.

A second conductive pattern 682 or RBL may be connected to source/drainof each of the selection transistors arranged in the first direction andmay extend in the first direction.

A third conductive 683 or WL may be connected to a gate of each of theselection transistors TR arranged in a second direction perpendicular tothe first direction and may extend in the second direction.

A fourth conductive pattern 684 or WBL may be connected to one end ofeach of the first conductive patterns 110 arranged in the firstdirection and may extend in the first direction.

A fifth conductive pattern 685 or SL may be connected to the other endof each of the first conductive patterns 110 arranged in the firstdirection and may extend in the first direction.

FIG. 27 illustrates a magnetic memory device according to anotherexample embodiment of the present disclosure.

Referring to FIG. 27, a magnetic memory device 97 includes a pluralityof magnetic tunnel junctions. The magnetic memory device 97 includes aplurality of magnetic tunnel junctions 101 arranged in a matrix format,a first conductive pattern 110 disposed adjacent to a free magneticlayer 120 of the magnetic tunnel junction 101, and a spin filterstructure 111 disposed on at least one of the opposite side surfaces ofthe first conductive pattern 110. The first conductive pattern 110provides a spin-orbit torque (SOT) caused by a spin-orbit coupling forcebetween the free magnetic layer 120 and the first conductive pattern110, and the spin filter structure 111 supplies spin-polarized currentto the first conductive pattern 110.

The first conductive pattern 110 may be periodically disposed on asubstrate plane in a first direction, and a magnetic free layer 120 ofeach of the magnetic tunnel junctions arranged in the first directionmay be periodically disposed adjacent to the first conductive pattern110. The first conductive pattern 110 may supply spin current to thefree magnetic layer 120 and may apply a spin-orbit torque to the freemagnetic layer 120. The spin-orbit torque may contribute tomagnetization reversal of the free magnetic layer 120.

A second conductive pattern 782 may be electrically connected to apinned magnetic layer 140 of each of the magnetic tunnel junctionsarranged in the first direction and may extend in a second directionperpendicular to the first direction.

A first selection transistor TR1 may be connected to one end of thefirst conductive pattern 110.

A second selection transistor TR2 may be connected to the other end ofthe first conductive pattern 110.

A third conductive pattern 783 or WBL may be connected to source/drainof the first selection transistors TR1 disposed in the first directionand may extend in the first direction.

A fourth conductive pattern 784 or SL may be connected to source/drainof the second selection transistor TR2 disposed in the first directionand may extend in the first direction.

A fifth conductive pattern 785 may connect a gate of the first selectiontransistor TR1 disposed in a second direction perpendicular to the firstdirection and a gate of the second selection transistor TR2 disposed inthe first direction to each other to extend in the second direction.

FIG. 28 illustrates a magnetic memory device according to anotherexample embodiment of the present disclosure.

Referring to FIG. 28, a magnetic memory device 98 includes a pluralityof magnetic tunnel junctions. The magnetic memory device 98 includes aplurality of magnetic tunnel junctions 101 arranged in a matrix format,a first conductive pattern 110 disposed adjacent to a free magneticlayer 120 of the magnetic tunnel junction 101, and a spin filterstructure 111 disposed on at least one of the opposite side surfaces ofthe first conductive pattern 110. The first conductive pattern 110provides a spin-orbit torque (SOT) caused by a spin-orbit coupling forcebetween the free magnetic layer 120 and the first conductive pattern110, and the spin filter structure 111 supplies spin-polarized currentto the first conductive pattern 110.

The first conductive pattern 110 may be periodically disposed on asubstrate plane in a first direction, and a magnetic free layer 120 ofeach of the magnetic tunnel junctions arranged in the first directionmay be periodically disposed adjacent to the first conductive pattern110. The first conductive pattern 110 may supply spin current to thefree magnetic layer 120 and may apply a spin-orbit torque to the freemagnetic layer 120. The spin-orbit torque may contribute tomagnetization reversal of the free magnetic layer 120.

A first selection transistor TR1 may be connected to a pinned magneticlayer 140 of the magnetic tunnel junction.

A second selection transistor TR2 may be connected to one end of thefirst conductive pattern 110.

A second conductive pattern 882 or RBL may be connected to source/drainof the first selection transistor TR1 disposed in the first directionand may extend in the first direction.

A third conductive pattern 883 or WBL may be connected to the other endof the first conductive pattern 110 disposed in the first direction andmay extend in the first direction.

A fourth conductive pattern 884 or SL may be connected to source/drainof the second selection transistor TR2 disposed in the first directionand may extend in the first direction.

A fifth conductive pattern 885 or WL may connect gates of the firstselection transistors TR1 arranged in a second direction perpendicularto the first direction and may extend in the second direction.

A sixth conductive pattern 886 or WL may connect gates of the secondselection transistors TR2 arranged in the second direction and mayextend in the second direction.

Referring to FIGS. 21 to 28, the free magnetic layer 120 may include atleast one a magnetic domain structure. The magnetic domain structure maybe a magnetic wall or a skyrmion.

Referring to FIGS. 21 to 28, the first conductive pattern 110 may applyin-plane current and may include an antiferromagnetic layer. The firstconductive pattern 110 may provide an in-plane exchange bias magneticfield to the free magnetic layer 120.

Referring to FIGS. 21 to 28, the first conductive pattern 110 may applyin-plane current and may include an antiferromagnetic layer and aferromagnetic layer which are sequentially stacked. Theantiferromagnetic layer may be disposed adjacent to the free magneticlayer, and the ferromagnetic layer may have an in-plane magnetizationdirection. The first conductive pattern may provide an in-plane exchangebias magnetic field to the free magnetic layer, and the free magneticlayer may be switched without an external magnetic field.

Referring to FIGS. 21 to 28, a magnetic tunnel junction may furtherinclude an auxiliary insulating layer disposed between the firstconductive pattern 110 and the free magnetic layer 120.

Referring to FIGS. 21 to 28, the first conductive pattern 110 mayinclude a first conductive pattern non-magnetic layer and a firstconductive pattern magnetic layer which are sequentially stacked, andthe first conductive pattern magnetic layer may include an in-planemagnetization direction component.

Referring to FIGS. 21 to 28, the first conductive pattern 110 mayinclude a first conductive pattern magnetic layer and a first conductivepattern non-magnetic layer which are sequentially stacked and mayinclude a non-magnetic layer disposed between the first conductivepattern magnetic layer and the free magnetic layer.

As described above, a magnetic tunnel junction device according to anexample embodiment of the present disclosure includes a spin filter (SF)structure which includes a magnetic field whose spin polarization (SP)is greater than 0 and equal to or smaller than 1. By abutting the spinfilter structure onto a portion beside a conducting wire in aconventional SOT junction structure, the amount and direction of a spingenerated according to injected current may controlled to increase spinaccumulation or improve spin-orbit torque efficiency. Thus, the injectedcurrent may be reduced to reduce power consumption. Moreover, when amagnetization direction of the spin filter (SF) and a magnetizationdirection of a free magnetic layer are parallel or antiparallel to eachother, an external magnetic field does not need to be applied, i.e.,field-free switching may be performed.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the following claims.

What is claimed is:
 1. A magnetic tunnel junction memory devicecomprising: a magnetic tunnel junction: a pinned magnetic layer, a freemagnetic layer, and a tunnel barrier layer interposed between the pinnedmagnetic layer and the free magnetic layer; a conductive pattern towhich in-plane direct current is configured to flow, the conductivepattern being disposed in contact with to the free magnetic layer of themagnetic tunnel junction to cause spin Hall effect or Rashba effect toapply a spin torque to the free magnetic layer of the magnetic tunneljunction to switch a magnetization direction of the free magnetic layerby the spin torque due to spin Hall effect or Rashba effect; and; a pairof spin filter structures disposed on the both side surfaces of theconductive pattern in a direction in which in-plane direct current isapplied, the spin filter structures have a fixed magnetizationdirection, wherein the spin filter structure filters are configured tofilter injected current to control the amount and direction of a spinand to supply the filtered current to the conductive pattern, whereinthe magnetization direction of the free magnetic layer is parallel oranti-parallel to the magnetization direction of the pinned magneticlayer, wherein the pair of spin filter structures have each otheranti-parallel magnetization directions, and wherein: the conductivepattern includes an antiferromagnetic layer and a ferromagnetic layerwhich are sequentially stacked, the antiferromagnetic layer is disposedadjacent to the free magnetic layer, the ferromagnetic layer has anin-plane magnetization direction, the conductive pattern is configuredto provide an in-plane exchange bias magnetic field to the free magneticlayer, and the free magnetic layer is configured to be switched withoutan external magnetic field.
 2. The magnetic tunnel junction device asset forth in claim 1, wherein the conductive pattern and the freemagnetic layer are aligned with each other.
 3. The magnetic tunneljunction device as set forth in claim 1, wherein the free magnetic layerhas perpendicular magnetic anisotropy (PMA).
 4. The magnetic tunneljunction device as set forth in claim 1, wherein a spin-flip diffusionlength of the conductive pattern is between 3 and 4 nanometers.
 5. Amagnetic tunnel junction memory device comprising: a magnetic tunneljunction: a pinned magnetic layer, a free magnetic layer, and a tunnelbarrier layer interposed between the pinned magnetic layer and the freemagnetic layer; a conductive pattern to which in-plane direct current isconfigured to flow, the conductive pattern being disposed in contactwith to the free magnetic layer of the magnetic tunnel junction to causespin Hall effect or Rashba effect to apply a spin torque to the freemagnetic layer of the magnetic tunnel junction to switch a magnetizationdirection of the free magnetic layer by the spin torque due to spin Halleffect or Rashba effect; and; a pair of spin filter structures disposedon the both side surfaces of the conductive pattern in a direction inwhich in-plane direct current is applied, the spin filter structureshave a fixed magnetization direction, wherein the spin filter structurefilters are configured to filter injected current to control the amountand direction of a spin and to supply the filtered current to theconductive pattern, wherein the magnetization direction of the freemagnetic layer is parallel or anti-parallel to the magnetizationdirection of the pinned magnetic layer, wherein the pair of spin filterstructures have each other anti-parallel magnetization directions, andwherein: the conductive pattern includes a conducting wire non-magneticlayer and a conducting wire ferromagnetic layer which are sequentiallystacked, and the conducting wire ferromagnetic layer includes anin-plane magnetization direction component.
 6. The magnetic tunneljunction device as set forth in claim 5, wherein the conductive patternand the free magnetic layer are aligned with each other.
 7. The magnetictunnel junction device as set forth in claim 5, wherein the freemagnetic layer has perpendicular magnetic anisotropy (PMA).
 8. Themagnetic tunnel junction device as set forth in claim 5, wherein aspin-flip diffusion length of the conductive pattern is between 3 and 4nanometers.
 9. A magnetic tunnel junction memory device comprising: amagnetic tunnel junction: a pinned magnetic layer, a free magneticlayer, and a tunnel barrier layer interposed between the pinned magneticlayer and the free magnetic layer; a conductive pattern to whichin-plane direct current is configured to flow, the conductive patternbeing disposed in contact with to the free magnetic layer of themagnetic tunnel junction to cause spin Hall effect or Rashba effect toapply a spin torque to the free magnetic layer of the magnetic tunneljunction to switch a magnetization direction of the free magnetic layerby the spin torque due to spin Hall effect or Rashba effect; and; a pairof spin filter structures disposed on the both side surfaces of theconductive pattern in a direction in which in-plane direct current isapplied, the spin filter structures have a fixed magnetizationdirection, wherein the spin filter structure filters are configured tofilter injected current to control the amount and direction of a spinand to supply the filtered current to the conductive pattern, whereinthe magnetization direction of the free magnetic layer is parallel oranti-parallel to the magnetization direction of the pinned magneticlayer, wherein the pair of spin filter structures have each otheranti-parallel magnetization directions, and wherein: the conductivepattern includes a conducting wire ferromagnetic layer and a conductingwire non-magnetic layer which are sequentially stacked, and anon-magnetic layer is provided between the conducting wire ferromagneticlayer and the free magnetic layer.
 10. The magnetic tunnel junctiondevice as set forth in claim 9, wherein the conductive pattern and thefree magnetic layer are aligned with each other.
 11. The magnetic tunneljunction device as set forth in claim 9, wherein the free magnetic layerhas perpendicular magnetic anisotropy (PMA).
 12. The magnetic tunneljunction device as set forth in claim 9, wherein a spin-flip diffusionlength of the conductive pattern is between 3 and 4 nanometers.